When Britain’s Team Sky cycling team made its debut in 2010, two things dominated its agenda. It planned to develop a British Tour de France winner within five years, and to do so with a zero-tolerance approach to doping.

Under Dave Brailsford, its chief executive, Sky’s roster excluded cyclists and staff members who had any past involvement in doping. He swiftly purged anyone on his payroll who became the subject of doping allegations.

The team reached its first objective ahead of expectations when Bradley Wiggins won the Tour de France in 2012. With Chris Froome, a Kenyan-born Briton, as its leader, Team Sky went on to win three of the past four editions of cycling’s largest event. Sky transformed Britain from being almost a nonentity in professional road cycling into a world dominator.

In a sport repeatedly tainted by artificial performance enhancement, that record inevitably led to raised eyebrows and unproven suspicions.

But as cycling’s world championships wind up today in Doha, Qatar, a dark cloud has descended over both Wiggins’ career and Sky’s sometimes self-righteous claims of doping purity. No one is suggesting Wiggins or the team broke any anti-doping rules. But the release of Wiggins’ World Anti-Doping Agency files by Russian hackers has prompted several prominent members of the professional cycling community to suggest Sky is, at the least, pushing to the limits of where the rules kick in. It also has become clear that Sky uses WADA’s exemption system for therapeutic drug use in a way many other cycling teams long ago rejected because of ethical concerns.

“With Sky, it’s either intentional malevolence, or the other possibility is that they weren’t fully aware of what that action meant because they effectively eliminated anyone with any doping experience in their employment base,” said Jonathan Vaughters, a former rider who confessed to doping and who is the chief executive of the U.S.-based Cannondale-Drapac cycling team.

The critics even include some members of Team Sky.

“You can do whatever you want against Wiggins, but unfortunately, as far as ethically, it’s wrong he is within the rules,” Nicolas Roche, an Irish cyclist who is switching teams for next season, told Cyclingnews at the world championships. “It is wrong that these rules are like that. That’s where the main problem is.”

The drug at the center of the controversy, triamcinolone acetonide, when used without permission is an old-fashioned sort of performance enhancer. Unlike many modern forms of doping, it is easily detected in tests.

Triamcinolone belongs to a group of hormones known as corticosteroids. Its powerful anti-inflammatory effects are useful for cheating in a sport like cycling in which riders can spend hours racing every day for three weeks. It also reduces body weight, another attraction in a sport in which top riders obsess over leanness.

The hacked WADA records indicate that from 2011 to 2013, Wiggins was given a permit for medically required use of triamcinolone. The therapeutic use exemption that has been the subject of the most scrutiny came before he won the Tour in 2012. Brailsford and Wiggins, however, have given extensive interviews with some British news media outlets about the triamcinolone permits.

In them, Wiggins said he suffers so badly from asthma and hay fever that antihistamines, the conventional allergy treatment, did not bring him relief. According to Wiggins, a specialist doctor recommended by the team’s medical staff said intramuscular injections of triamcinolone would end his symptoms.

“One thing I would constantly have is a blocked nose,” Wiggins told The Guardian. “People would say, ‘Have you got a cold? You’re not ill, are you?’ No, I’ve got hay fever, allergies. It was just a constant thing.”

Speaking with the BBC, Brailsford repeatedly said that the treatment was recommended by a specialist and then reviewed, and approved, by the International Cycling Union.

“I trust and believe in the integrity of the process,” Brailsford said, adding: “But let’s get back to the fact that it wasn’t being used to enhance performance. This was a recognized treatment.”

But teams, including Cannondale-Drapac, which belong to the Movement for Credible Cycling, a group founded in 2007, take a much different approach to corticosteroids, including triamcinolone.

In the interests of the riders’ health and to prevent the treatment from providing a performance enhancement, Roger Legeay, the group’s president, said all riders on teams in the organization who received corticosteroids were then suspended from racing for a minimum of eight days. After that time, they are given a blood test. If it shows the riders’ cortisone levels are below normal — a side effect of corticosteroids — the suspensions are extended.

Through the cycling union, Legeay’s group has been pushing for a ban on therapeutic exemption permits for any corticosteroid use.

“Because this is such a good way to improve performance, we have to be very suspicious about that gray area,” said Legeay, who, when he led a now-defunct French team, once employed Wiggins as a rider. “It is necessary to have a very clear rule, it is necessary for the credibility of sport.”

Vaughters, whose riders have not had any therapeutic exemptions this season, said the group’s rule eliminates the possibility of turning an illness into a sanctioned way to enhance performance through inappropriate treatment.

“With all we’ve been going through in cycling, it’s just easier for us to tell the guy, ‘You’re sick, take the medicine, you’re not going to race for two or three weeks.’”

Ben Wright, a spokesman for Team Sky, said the team has made changes and, among other things, now requires two team doctors to approve any application for a therapeutic exemption. To date, Sky has received 13 of the permits.

Brailsford, he added, hopes to develop a system that will allow the team to publicize its application. But getting there will require riders to waive medical privacy rights.

As for Wiggins, while he has vigorously defended his treatment and denied that it boasted his performance, he did acknowledge that others might not view it as ethical, whatever its legality.

“Straight off, the way cycling is today, yes, yes,” he told The Guardian. “Because it doesn’t take much in cycling in this day and age now because of what’s gone before. So I understand that.”